Synthesis, Isolation, and Spectroscopic Characterization of Ytterbium-Containing Metallofullerenes

A series of Yb-containing metallofullerenes, namely, Yb@C74 (I, II), Yb@C76 (I, II), Yb@C78, Yb@C80, Yb@C82 (I, II, III), and Yb@C84 (I, II, III, IV), was successfully synthesized and isolated by multistage HPLC for the first time. All of these isolated metallofullerenes were confirmed by LD-TOF mass spectrometry and characterized by UV-vis-NIR absorption spectroscopy. The valence state of the encaged ytterbium atoms, the probable molecular symmetries, and the electronic structures are discussed in terms of their HPLC behaviors and absorption spectra. In particular, two new monometallofullerene isomers based on C74 and C84 cages were isolated for the first time that are proposed to have completely novel cage structures not reported elsewhere so far.